GMC Sierra 2015 Owner's Manual page 60

Manual-Open/Manual-Close: To
open the sunroof, press and hold
the rear of the SLIDE switch until
the sunroof reaches the desired
position. Press and hold the front of
the SLIDE switch to close it
Express-Open/Express-Close: To
express-open the sunroof, fully
press and release the rear of the
SLIDE switch until the sunroof
reaches the desired position. To
express-close the sunroof, fully
press and release the front of the
SLIDE switch. Press the switch
again to stop it.
When the sunroof is opened, an air
deflector will automatically raise.
The air deflector will retract when
the sunroof is closed.
The sunroof also has a sunshade,
which can be pulled forward to block
sun rays. The sunshade must be
opened and closed manually.
If an object is in the path of the
sunroof while it is closing, the
anti-pinch feature will detect the
object and stop the sunroof.
Dirt and debris may collect on the
sunroof seal or in the track. This
could cause an issue with sunroof
operation or noise. It could also plug
the water drainage system.
Periodically open the sunroof and
remove any obstacles or loose
debris. Wipe the sunroof seal and
roof sealing area using a clean
cloth, mild soap, and water. Do not
remove grease from the sunroof
tracks.
If water is seen dripping into the
water drainage system, this is
normal.
Keys, Doors, and Windows 2-23